In recent years, gold nanocolloids (e.g., nanoparticles, nanorods, and nanostars) have generated much interest for use in biomedical research, due to their unique plasmonic features and reported low cytotoxicity. Synthetic methodologies such as hot-injection of gold precursors in oleylamine solution and hexadecyltrimethylammonium bromide-stabilized seeded growth were developed to prepare gold nanostructures with various sizes and shapes. Integration of the as-synthesized nanomaterials into biology requires access to hydrophilic nanocrystals with guaranteed long-term colloidal stability and bio-compatibility. We hereby introduce a photo-promoted ligand exchange of gold colloids with a series of lipoic acid (LA)-based ligands (including monomeric and polymeric ligands), which can be rapidly implemented (with times requited of ~20 - 30 min.), while consuming substantially smaller amounts of ligands, compared to “conventional” phase transfer strategies. We applied this procedure to several gold colloids with great success. The strategy also allows the introduction of various reactive groups onto the nanocrystal surfaces. For instance, ligation with polymeric ligands made of LA and PEG-modified poly(isobutylene-<i>alt</i>-maleic anhydride), can easily provide nanocolloids surface functionalized with controllable numbers of carboxylic acids, amines or azides. The final nanomaterials have been characterized using dynamic light scattering, transmission electron microscopy, pH-stability tests, and further tested in sensor design.

Photoligation with lipoic acid ligands is an effective strategy for preparing biocompatible gold colloids

2019 Spring National Meeting

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